This experiment evaluated the effects of two fat sources on performance, some blood parameters and carcass characteristics of broiler chicks. One hundred and eighty day-old broiler chicks were randomly assigned to five dietary treatments (three replicates of 12 birds per treatment). The experiment was performed as a completely random design (CRD) and birds were fed isoenergetic and isonitrogenous diets containing no fat (control), 20 and 40 g soyabean oil, 20 and 40 g beef tallow/kg feed from 11 -42 d of age. Food intake and body weight gain both increased significantly with supplemental level of both fat sources, the rate in food intake being higher with soyabean oil than with beef tallow. Feed conversion ratio decreased significantly with both sources in the period 29 " 42 d. Serum triglyceride and very low density lipoprotein (VLDL) contents were unaffected by dietary oil inclusion but cholesterol, high-(HDL) and low (LDL) density lipoprotein contents increased significantly with oil level. Serum glucose (GLU) content decreased significantly with increasing oil inclusion. In all cases the blood parameters responded significantly differently to the two supplemental fat sources with the rate of reduction in GLU, cholesterol and LDL, and the rate of increase in TG, HDL and VLDL being greater with soyabean oil than with beef tallow. Liver and abdominal fat percentages increased significantly with supplemental fat inclusion. The results indicate that supplementation of broiler diets with up to 40 g soyabean oil/kg feed significantly improved the performance and reduced serum cholesterol, LDL and abdominal fat in comparison with chicks receiving diets containing beef tallow.